Numerous exercises have been used for developing abdominal muscles. Such exercises include sit ups, leg raises, rollovers, leg press-outs and others. Since these exercises are normally performed without any apparatus, adequate resistance is not provided. Additionally, these exercises place strain on other muscles, in addition to the abdominal muscles, such that the abdominal muscles are not effectively isolated.
Conventional exercises present numerous problems For example, in leg lifts, stress is exerted on the leg muscles as well as the abdominal muscles. Since leg muscles often tire before the abdominal muscles, development of the abdominal muscles is limited. Also these exercises require increasing the repetitions since the resistance cannot be effectively increased. This increases the amount of time necessary for performing adequate exercise. Further, the conventional exercises, in stressing the back muscles, can lead to permanent damage of the back muscles.
Additionally, sophisticated machines have been developed as abdominal exercise apparatus. However, these apparatus have tended to be complex to use and expensive.